This invention relates to a method and apparatus for testing flow control valves and more particularly, the testing of the flow control valves of an anesthesia delivery apparatus.
The vast majority of hospitals, clinics and other health care institutions utilize gas anesthesia in administering health care to their patients. The preferred method is to utilize an anesthesia machine to control the flow of these gases to and from the patient. Because a patient's life may depend upon the proper administration of anesthesia, it is critical that the health care provider ensure that an anesthesia machine is functioning correctly.
A gas anesthesia machine is an extremely complex piece of equipment. It regulates the flow of anesthesia gases, typically O.sub.2 and N.sub.2 O. It controls the mixture of these gases and an anesthetic agent as well as the removal of CO.sub.2 from the gases as they flow through the system.
The gas anesthesia machine may be broken down into several systems, each performing a specific function. The control system consists of a complex system of valves, regulators, vaporizers and manifolds which precisely control the mixture of the gases and anesthesia agents and the pressure at which this mixture is provided at the machine or common gas outlet port. The patient system or circuit consists of an absorber, inhalation and exhalation check valves, a pressure limiting valve and a corrugated breath circuit attached to a mask for controlling the delivery of anesthesia to the patient.
In a typical rebreathing system, the absorber may contain one or more canisters of absorbent granules for removing CO.sub.2 from the gas. The input to the absorber is connected through a pressure limiting valve and rebreathing bag to the exhalation check valve and the exhalation port. The output of the absorber is connected to the inhalation check valve and the inhalation port. In a non-rebreathing system, an absorber is not used and the anesthetic gas is delivered directly from the control system to the patient.
The inhalation and exhalation check valves control the flow of anesthesia gas to and from the patient. When a patient inhales, the inhalation check valve opens to permit the free flow of essentially CO.sub.2 -free anesthesia gas to the patient. At the same time, the exhalation check valve closes, preventing previously exhaled gases from being inhaled. When the patient exhales, the exhalation check valve opens and directs the flow of exhaled gases into the absorber for CO.sub.2 absorption. At the same time, the inhalation check valve closes preventing the mixture of anesthesia and exhaled gases.
As can be seen, if either or both these valves fail to function properly, there is a potential for serious injury to the patient. Therefore, it is extremely important that these valves be tested on a regular basis.
The current method for testing the valves requires an anesthetist to place the mask of the patient circuit over his or her own nose and mouth to breath into the system. Individual valves are tested by inhaling and exhaling into each port. Visual observation and feel enable the anesthetist to verify the functionality of the check valves. This method is unacceptable because it increases the risk of transmitting communicable diseases, including AIDS and hepatitis. Indeed, many clinicians do not perform this very important machine valve test, fearing exposure of communicable diseases from the anesthesia machine.
The present invention provides a method and apparatus for testing the functionality of inhalation and exhalation check valves which virtually eliminates the risk of transmitting disease. The present invention includes a relatively simple and inexpensive apparatus for manually creating an artificial source of positive and negative gas pressure. The application of positive and negative gas pressure to the inhalation and exhalation check valves permits an anesthetist to verify their functionality without exposing himself/herself or a patient to the increased risk of disease.
Accordingly, it is one object of the present invention to provide an improved method and apparatus for testing flow control valves.
Another object of the present invention is to provide an improved method and apparatus for testing check valves in an anesthesia machine.
It is another object of the present invention to provide an improved method and apparatus for testing check valves in an anesthesia machine that provides for the reduced risk of transmitting disease to the patient and the anesthetist.
It is a further object of the present invention to provide an improved apparatus for testing check valves in an anesthesia machine that is inexpensive to produce and simple to use.
Other objects will be apparent from the disclosure which follows.